[PATCH -next] platform/chrome: Make function wilco_ec_transfer() static

[Wei Yongjun <weiyongjun1@xxxxxxxxxx>]

Fixes the following sparse warning:

drivers/platform/chrome/wilco_ec/mailbox.c:126:5: warning:
 symbol 'wilco_ec_transfer' was not declared. Should it be static?

Fixes: 436dad4fda10 ("platform/chrome: Add new driver for Wilco EC")
Signed-off-by: Wei Yongjun <weiyongjun1@xxxxxxxxxx>
---
 drivers/platform/chrome/wilco_ec/mailbox.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/platform/chrome/wilco_ec/mailbox.c b/drivers/platform/chrome/wilco_ec/mailbox.c
index c7028488e575..f6ff29a11f1a 100644
--- a/drivers/platform/chrome/wilco_ec/mailbox.c
+++ b/drivers/platform/chrome/wilco_ec/mailbox.c
@@ -123,8 +123,9 @@ static void wilco_ec_prepare(struct wilco_ec_message *msg,
  * Context: ec->mailbox_lock should be held while using this function.
  * Return: number of bytes received or negative error code on failure.
  */
-int wilco_ec_transfer(struct wilco_ec_device *ec, struct wilco_ec_message *msg,
-		      struct wilco_ec_request *rq)
+static int wilco_ec_transfer(struct wilco_ec_device *ec,
+			     struct wilco_ec_message *msg,
+			     struct wilco_ec_request *rq)
 {
 	struct wilco_ec_response *rs;
 	u8 checksum;